Paving unit

ABSTRACT

A interlocking paving unit has a top surface ( 2 ) and a plurality of side surfaces ( 4, 5 ), with at least one of the side surfaces ( 4, 5 ) of the paving unit being provided with at least one substantially vertically extending, substantially asymmetric protrusion ( 10 ). The protrusion ( 10 ) comprises a first ridge portion ( 11 ) and a second portion ( 12 ) being spaced apart by an intermediate portion ( 13 ). The protrusion ( 10 ) is locatable in a complementary recess on an adjacent paving unit, wherein the interengagement between the protrusion and the recess provides interlock between the paving unit and an adjacent paving unit.

FIELD OF THE INVENTION

[0001] The present invention is directed to improvements in or relatingto paving units. More particularly the present invention relates topaving units having the capability of forming an integral structuralsurface.

BACKGROUND OF THE INVENTION

[0002] In this specification, where a document, act or item of knowledgeis referred to or discussed, this reference or discussion is not anadmission that the document, act or item of knowledge or any combinationthereof was at the priority date:

[0003] (i) part of common general knowledge; or

[0004] (ii) known to be relevant to an attempt to solve any problem withwhich this specification is concerned.

[0005] Whilst the following discussion concerns paving units, theirinstallation and manufacture, in particular, paving units capable ofinterlocking with adjacent paving units, it is to be understood that thesame principles apply to paving units of any shape or colour.

[0006] Small element paving comprises a plurality of paving unitsarranged together to provide a paved surface. Over the last thirty yearssmall element paving has developed from its initial use as a surface forfootpaths and other light duty applications to use as an integralstructural surface for heavy duty pavements. Heavy duty pavements areused for example at ports, trucking stations, on roads, at bus stops andat airports.

[0007] Such structures must be resistant to the movement of individualpaving units relative to one another. If a paving unit is separated fromits adjacent paving unit, whether it be due to subsidence of the groundon which the paving unit is laid or to a breakdown in the connectionbetween adjacent paving units, it is likely to present a gap or anotherwise uneven surface.

[0008] It will be apparent that that is a potentially dangeroussituation, as a pedestrian may catch a heel or the toe of a shoe in thegap created, and may trip and fall. Depending on the width of the gap,it may also have adverse consequences for the tyres and wheels and hencethe suspension system of trucks and aircraft, and may lead to acatastrophic outcome if any of those elements was to fail.

[0009] A dislodged paving unit may also pose a risk to the turbines ofaircraft engines if a loose paving unit was drawn into the engine.

[0010] Standard paving units have proved to be inefficient as they donot inherently have sufficient ‘interlock’.

[0011] The concept of interlock relates to the ability of an individualpaving unit to articulate independently of an adjacent unit withoutbeing dislodged from the overall paving structure.

[0012] Three forms of interlock should ideally be present in a blockpaving system, namely:

[0013] rotational interlock, which is achieved by the presence of edgerestraints.

[0014] vertical interlock, which is provided by the presence of stablecompacted sand between all adjacent units.

[0015] horizontal interlock, which is achieved by a combination oflaying paving units in a herringbone pattern and by the use of shapedunits.

[0016] These forms of interlock are intended to prevent paving unitsfrom ‘creeping’, that is, moving horizontally when a force is applied tothe paving unit in a direction which is not perpendicular to an upperface of the unit. It is also intended to resist rotational and verticalmovement relative to an adjacent unit.

[0017] Small element paving units rely on the continuous presence ofcompacted sand between individual paving units to provide the necessary‘interlock’ to resist horizontal, vertical and/or rotationaldisplacement of the paving unit. This sand also inhibits ingress ofwater into the underlying pavement structure. Displacement may manifestitself when a substantial weight is repeatedly placed on an individualunit by, for example, continuous trafficking over an individual unit.

[0018] Further displacement can occur as a result of changes in theunderlying substratum on which the paving is laid.

[0019] Unfortunately, the sand which provides the interlock between theadjacent paving units can, over a period of time, be displaced from thejoints by various agents of erosion such as jet blast, use of vacuumsweepers, water flow, and degradation and liquefaction of laying coursematerials, thereby resulting in a loss of interlock.

[0020] The loss of sand in the joints negates the interlock which canlead to serious deformation and eventual disintegration of the pavingsurface as shown in FIGS. 8 to 13.

[0021] Earlier attempts to provide further interlock between individualpaving units consisted of designing various shapes to increaseinterlock. This included E-shaped, Y-shaped and L-shaped paving unitswith a plurality of engagement points for adjacent paving units.

[0022] Although these various shapes have been tested, it has beenobserved that problems still persist as shaped paving units may notprovide sufficient interlock for use as part of heavy duty pavements.These paving units are also costly to manufacture and time consuming tolay given their often convoluted design.

[0023] Other attempts to provide suitable heavy duty pavements includethe adoption of a mechanical locking device involving complementaryrecesses and protrusions on adjacent paving units. This feature provideda further degree of interlock between adjacent paving units.

[0024] However, whilst an apparent improvement, “self-locking” pavingunits do not readily resist vertical or horizontal movements. The pavingunits can also be rotated and become uneven should there be a slightdeformation in the overall pavement either by external pressure or bychanges in the underlying ground. Hence these are consequentlyunsuitable for heavy duty pavements with constant traffic.

[0025] Similarly, these paving units are also unsuitable for airports asjet aircraft engines can provide a suction effect that can result in thedisplacement of the individual paving units.

SUMMARY OF THE INVENTION

[0026] The present invention accordingly provides in one embodiment apaving unit for use as part of a paving arrangement, the paving unithaving a top surface and a plurality of side surfaces with one of theside surfaces of the paving unit being provided with at least onesubstantially asymmetric vertically extending tongue when the pavingunit is in an as laid form, the tongue comprising a ridge portion and asubstantially tapering second portion, the ridge portion and thetapering portion being spaced apart by a substantially planarintermediate portion, the tongue capable of engaging a complementarygroove in an adjacent paving unit, the groove only being open to theextent that the groove permits the tongue to be inserted into andenclosed within the groove, wherein the interengagement between thetongue and the groove provides interlock between the paving unit and anadjacent paving unit.

[0027] The paving unit according to the invention has been found toprovide a degree of interlock to reduce the incidence of vertical androtational movement of the paving unit. The interlock is enhanced by thedimensions of the protrusion/complementary recess and the engagementtherein.

[0028] The tapering may be towards or away from a side surface of thepaving unit Preferably the second portion tapers in the direction of aside surface of the paving unit.

[0029] An outer surface of the intermediate portion typically extends ina direction which is substantially parallel to a side surface of thepaving unit.

[0030] The top surface of the paving unit can take any suitable shape.Preferably the top surface of adjacent paving units is of substantiallysimilar configurations. Preferably the top surface is substantiallyplanar. The top surface may be of a substantially rectangularconfiguration. It may be of substantially square configuration. It maybe of another polygonal configuration, such as a hexagon. Other topsurface shapes are envisaged within the scope of the invention.

[0031] In a typical preferred configuration, a paving unit according tothe invention has on opposed side surfaces at least one protrusion asdescribed and at least one complementary recess to receive a protrusionas described.

[0032] In an alternative arrangement within the scope of the invention,opposed side surfaces may both carry protrusions. In another alternativearrangement, the opposed sides may carry complementary recess(es).Alternatively, opposed sides may have a combination of protrusions andrecesses. In these preferred embodiments, adjacent paving units willhave either protrusions, complementary recesses or a suitablecombination to allow for interengagement and interlock.

[0033] A paving unit according to the invention having a substantiallyrectangular configuration will typically have on its opposed shorterside spices at least one protrusion and at least one complementaryrecess. Alternatively, opposed shorter side surfaces may both haveprotrusions. Alternatively, opposed shorter side surfaces may havecomplementary recesses. Alternatively, opposed shorter side surfaces mayhave a combination of protrusions and recesses. In the latterembodiments, adjacent paving units will of course have eitherprotrusions, complementary recesses or a suitable combination to allowfor interengagement and interlock with adjacent paving units.

[0034] According to a further preferred form of the invention, thepaving units may be manufactured in a wide range of colours. Preferablythe top surface of the paving unit will include an at least partlyreflective surface. The reflective surface may take any suitable form.It will typically be integral with the top surface of the paving unit,although it may be provided by the application of a composite mix to thesurface. The reflective surface may be formed by the application of areflective mix.

[0035] According to a further preferred form of the invention, thepaving units may include a noise reducing agent. The noise reducingagent may take any suitable form. Preferably the noise reducing agent isprovided in part by chamfering edges of the paving unit.

[0036] The present invention provides in another embodiment a pavementcomprising an array of paving units as described above interlocked bysaid tongue and groove arrangement to form a substantially continuouspavement.

[0037] The pavement will typically be constructed by fitting pavingunits with complementary side surfaces adjacent to one another, such asside by side with one another or end to end. Side surfaces of the pavingunits can as described herein include various combinations ofprotrusions and complementary recesses arranged to interengage adjacentpaving units, thereby providing an interlocked pavement.

[0038] A pavement according to the invention may take any suitable form.Preferably the paving units are of a substantially rectangularconfiguration. The paving units may be arranged in a herringboneconfiguration to enhance the degree of interlock. Other pavementconfigurations are envisaged within the scope of the invention.

[0039] The present invention provides in another embodiment a method forlaying a multiplicity of paving unit as described above, the methodcomprising the step of interlocking in a final laying pattern saidmultiplicity of paving units to form a pallet, and mechanically layingthe paving units by securing and placing the whole layer onto theprepared base.

[0040] The method may further include the step of interengaging edges ofadjacent layers during a mechanical laying step to form a pavement.

[0041] Layers can subsequently engage adjacent layers with the pavingunits of one layer interengaging the protrusions or recesses of pavingunits of the adjacent layer. In this way a continuous pavement can berapidly laid. The interlock provided by the interengagement ofprotrusions and complementary recesses is also intended to reduce theincidence of paving units becoming dislodged during a pallet formingoperation.

DESCRIPTION OF THE DRAWINGS

[0042] The invention will now be further explained and illustrated byreference to the accompanying drawings in which:

[0043] FIGS. 1 to 4 are perspective views of a paving unit according toone embodiment of the present invention;

[0044]FIG. 5 is a side view of the paving unit of FIGS. 1 to 4 arrangedas part of a pavement;

[0045]FIG. 6 is a plan view of the pavement of FIG. 5;

[0046]FIG. 7 is a cross sectional view of the pavement of FIG. 5; and

[0047] FIGS. 8 to 13 are examples of problems associated with standardpaving units of the prior art.

[0048] Turning to the drawings, a paving unit 1 includes a top surface 2and a plurality of side surfaces 3, 4, 5 and 6. In this preferredembodiment, the top surface 2 is of a substantially rectangular prismconfiguration although other configurations are envisaged within thescope of the invention. As a consequence of its rectangularconfiguration, the paving unit 1 has opposed longer side surfaces 3 and4 and opposed shorter side surfaces 5 and 6.

[0049] As is shown in FIGS. 3 and 4, a longer side surface 3 has a pairof asymmetric protrusions 10. Each protrusion extends substantiallyvertically from side surface 3 and tapers outwards from the sidesurface. Each protrusion includes a ridge portion 11 and a secondportion 12, ridge portion 11 and second portion 12 being spaced apart byan intermediate portion 13. As is shown in FIGS. 2 and 4 a protrusion 10is also located on a shorter side surface 5.

[0050] As shown in FIGS. 1 and 2, the remaining longer side surface 4has a pair of complementary recesses 20. The dimensions of the recesses20 correspond to the extended dimensions of the protrusions 10.Consequently, a protrusion 10 of an adjacent paving unit may be locatedwithin the recess 20. The dimensions of the protrusions 10 andcomplementary recesses 20 and the interengagement between them providesinterlock between adjacent paving units to reduce the incidence verticaland rotational movement.

[0051] As is shown in FIGS. 1 to 4, second portion 12 tapers towards theside surface of the paving unit 1. The intermediate portion 13 is in theembodiment shown substantially planar, with an outer surface extendingapproximately parallel to the side surface to give the appearance of atongue like projection. The corresponding recesses can be convenientlyconsidered as a complementary groove.

[0052] The paving unit 1 may be manufactured in a wide range of colours.The top surface 2 may include an integral reflective surface (notshown). The paving units may also include a noise reducing agent. Asshown in FIGS. 1 to 4, the top edges 30 of the paving unit 1 arechamfered edges of the paving unit.

[0053] As shown in FIGS. 5 and 6 a plurality of paving units 1 can bearranged to form a pavement by fitting paving units 1 with complementaryside surfaces to allow for inter engagement and provide a degree ofinterlock. As is shown in FIG. 6, the paving units can be arranged in aherringbone arrangement to maximize inter lock. As is shown in FIG. 12the pavement results in a mat like structure to accommodate forsubstantial deformation or ground settlement.

[0054] A multiplicity of paving 1 can be interlocked in a final layingpattern to form a pallet, whereby to facilitate mechanical laying of thepallet. Pallets can subsequently engage adjacent pallets with the pavingunits of one pallet interengaging the protrusion 10 or recesses 20 ofpaving units 1 of the adjacent pallet. In this way a continuous pavementcan be rapidly laid. The interlock provided by the interengagement ofprotrusions and complementary recesses is also intended to reduce theincidence of paving units becoming dislodged during a pallet formingoperation.

[0055] The word ‘comprising’ and forms of the word ‘comprising’ as usedin this description and in the claims does not limit the inventionclaimed to exclude any variants or additions. Modifications andimprovements to the invention will be readily apparent to those skilledin the art. Such modifications and improvements are intended to bewithin the scope of this invention.

The claims defining the invention are as follows:
 1. A paving unit foruse as part of a paving arrangement, the paving unit having a topsurface and a plurality of side surfaces with one of the side surfacesof the paving unit provided with at least one substantially asymmetricvertically extending tongue when the paving unit is in an as laid form,the tongue comprising a ridge portion and a substantially taperingsecond portion, the ridge portion and the tapering portion being spacedapart by a substantially planar intermediate portion, the tongue capableof engaging a complementary groove in an adjacent paving unit, thegroove only being open to the extent that the groove permits the tongueto be inserted into and enclosed within the groove, wherein theinterengagement between the tongue and the groove provides interlockbetween the paving unit and all adjacent paving unit.
 2. The paving unitaccording to claim 1 wherein the tongue is tapered.
 3. The paving unitaccording to claim 2 wherein the tongue tapers towards a side surface ofthe paving unit.
 4. The paving unit according to claim 1 wherein thesecond portion tapers towards a side surface of the paving unit.
 5. Thepaving unit according to claim 1 wherein the intermediate portionextends in a direction which is substantially parallel to a side surfaceof the paving unit.
 6. The paving unit according to claim 1 wherein thetop surface of the paving unit is of substantially similar configurationas an adjacent paving unit.
 7. The paving unit according to claim 1wherein the top surface is of a substantially rectangularconfigurations.
 8. The paving unit according to claim 1 wherein thepaving unit has on opposed side surfaces at least one tongue and atleast one complementary groove to receive a protrusion.
 9. The pavingunit according to claim 1 wherein opposed side surfaces both carrytongues.
 10. The paving unit according to claim 1 wherein opposed sidesurfaces both carry complementary groove(es).
 11. The paving unitaccording to claim 1 wherein opposed side surfaces both have acombination of tongues and groves.
 12. The paving unit according toclaim 1 wherein the top surface of the paving unit includes an at leastpartly reflective surface.
 13. The paving unit according to claim 12wherein the reflective surface is provided by the application of an atleast partially reflective layer to the top surface of the paving unit.14. The paving unit according to claim 1 wherein the paving unitincludes a noise reducing agent.
 15. The paving unit according to claim14 wherein the noise reducing agent is provided in part by chamferingthe edges of the paving unit.
 16. A pavement comprising an array ofpaving units, the paving units being as claimed in any preceding claiminterlocked by said groove and tongue arrangement to form asubstantially congruous pavement.
 17. The pavement according to claim 16wherein the paving units are arranged with complementary side surfacesadjacent to one another.
 18. The pavement according to claim 16 whereinthe paving units are arranged in a herringbone pattern.
 19. A method forlaying a multiplicity of paving units, the paving units being as anyproceeding claim, the method comprising the step of interlocking in afinal laying pattern said multiplicity of paving units to form a layeron a pallet and mechanically laying the layer.
 20. The method accordingto claim 19 and further including the step of interengaging edges ofadjacent layers from the pallets during a mechanical laying step to forma pavement.